DEVELOPMENT OF VESSELS. 



21 



posed of these moniliform vessels has been denominated phlehoidal 

 (pXE^j fi>^E/3o5, a vein). 



Laticipeeous Vessels (latex, fluid, and fero, I bear) form the 

 tissue called Cinenchyma (xmu, I move, from movements observed in 

 their contents). They are the Milk-vessels, and the Proper vessels 

 of old authors, and have been particularly described by Schultz. They 

 consist of long, branched, homogeneous tubes, having a diameter of 

 about TTTiT of an inch, which unite or anastomose freely (fig. 68), 

 thus resembling the vessels of animals. At first the tubes are veiy 

 slender and uniformly cylindrical (fig. 69 a),- but afterwards they 

 enlarge and present irregular distensions at different parts of their 

 course (figs. 69 b, 70), giving rise to an articulated appearance. Their 

 walls vary in thickness, and are not marked by any depressions or 



Fig. 68. 



Jll 

 Fig. 69. 



Fig. ro. 



fibres. These vessels are met with in the inner bark, and they con- 

 tain a granular fluid called latex, which is at first transparent, but 

 often becomes of a white, yellow, or reddish colour. Some suppose 

 that these vessels are simply intercellular canals lined with a con- 

 tinuous membrane, containing a peculiar fluid. The tissue can be 

 easily examined in the India-rubber tree, in Dandelion, Lettuce, and 

 Celandine, and in various species of Ficus and Euphorbia. 



2. Development and Functions of Vessels. 



The simple cell is the form in which vegetable tissue first makes its 

 appearance. It is the primary form of all the textures subsequently 



Kg. 68. Laticiferous vessels (Cinenchyma) from Euphorbia dulcis. 

 of Latex from Celandine (Chelidimium majus). i 



Figs. 69, 70. Vessels 



